Typically, digital communication systems utilize circuit switching, i.e., time-division multiplexing (TDM), to provide voice and data communications between various voice stations and data terminals of the system. Increasingly, many applications require the circuit switched system to interconnect to a packet switched system. Optimal utilization of this interconnection requires that terminals and ports of the packet switched system be able to transfer data and effectuate control on terminals and ports of the circuit switched system and vice-versa. In the prior art, communications between a terminal of a circuit switched system and a terminal of a packet switched system required first establishing a dialed connection to the interface circuit and then establishing a dialed connection between the interface and the called terminal on the packet system. Thus, inter-system connections typically require an extra dialing step, compared to intra-system connections, which resulted in a time-consuming and inefficient operation.
What is desired is single-stage or direct dialing to eliminate the extra layer of system administration required on inter-system call set-up and a uniform terminal addressing plan across both systems to eliminate address translation on inter-system calls.